docstr: Add some data at the end of each signal (real-time signals).
docstr_tok: ["Add","some","data","at","the","end","of","each","signal","(","real-time","signals",")","."]
code: def on_timer(self, event):
      """Add some data at the end of each signal (real-time signals)."""
      k = 10
      y[:, :-k] = y[:, k:]
      y[:, -k:] = amplitudes * np.random.randn(m, k)
  
      self.program["a_position"].set_data(y.ravel().astype(np.float32))
      self.update()
      self.context.flush()
  
file_path: vispy/examples/demo/gloo/realtime_signals.py
imports: from vispy import gloo
  from vispy import app
  import numpy
  import math
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.on_timer(event) without return types